KR101356497B1 - Method For Transmitting RACH Using Variable RACH Structure, And Method For Repeating Sequence For Reducing The Influence Of Frequency Offset - Google Patents

Abstract

A RACH transmission method using various RACH structures, and a sequence repetition method for reducing the influence of frequency offset are disclosed. That is, according to an embodiment of the present invention, among the RACH structures having a plurality of TTI lengths to support a large cell, and having a variable number of preamble repetition structures, a cell size that can be supported and a RACH structure to be used are shown. It may be used in various combinations in consideration of the number of bits. In another embodiment of the present invention, an efficient sequence repetition method for solving a frequency offset problem is provided.

RACH, frequency offset

Description

Method for Transmitting RACH Using Variable RACH Structure, And Method For Repeating Sequence For Reducing The Influence Of Frequency Offset}

1 is a diagram illustrating RACH structures that support multiple TTI lengths to support large cells and have various numbers of preamble repetition structures.

2 is a view for explaining a sequence repetition method of reducing the influence of a frequency offset by dividing and relocating a preamble sequence into two parts according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining a method of repeatedly applying a sequence in accordance with one preferred embodiment of the present invention, and applying circular movement to a part of the repeating portion. FIG.

4 is a diagram for explaining a method of masking and applying a predetermined sequence to a preamble sequence according to another embodiment of the present invention;

The following description relates to a RACH transmission method using various RACH structures, and a sequence repetition method for reducing the influence of frequency offset.

To this end, the effects of the general RACH transmission structure and frequency offset are as follows.

The RACH is a channel used by a user equipment (UE) to obtain initial uplink synchronization. A channel used when the UE is first powered on or when it is in idle mode for a long time and becomes active again and needs to reconfigure uplink synchronization. Available channel.

RACH basically supports multiple users, and each UE transmits a specific preamble sequence when accessing the RACH, and when the base station recognizes this and transmits a signal in downlink, the UE uses the information. To update his time synchronization information. In this case, when the frequency synchronization information is transmitted together, the frequency synchronization information can also be used for the UE information.

The basic requirement for such a RACH is to satisfy the conditions for round trip delay and path loss regardless of UE speed, frequency offset, cell size, and the like. Currently, in the 3GPP LTE field, a RACH structure having a 1 ms TTI length, a preamble length of 0.8 ms, and a guard time of 100 ms has been discussed. Guard Time can cover up to 15 Km of cell size.

However, the cell size may be larger than 15 Km in some cases, and it is currently discussed that it should cover 30 Km or more. Therefore, there is a need for a method of using a RACH having a plurality of TTI lengths.

Meanwhile, since the aforementioned RACH preamble is a signal transmitted before a closed loop between the UE and the base station is generated, the RACH preamble is very vulnerable to a frequency offset as the UE generates and transmits a signal. Has Such a frequency offset may cause a problem that the base station receiving the RACH increases a false alarm rate or decreases a detection probability.

Therefore, research is being conducted on how to set up the RACH to cope with the effect of this frequency offset in the RACH transmission, and how the UE can transmit the RACH in accordance with the RACH configuration.

According to the above-described aspect, the following proposes various RACH structures having a plurality of TTI lengths to support a large cell, and available RACHs depending on the number of signaling bits and the use of a preamble repetition structure to indicate these structures. We want to define the combination of structures.

In addition, when repeatedly applying the sequence for the purpose of the RACH preamble sequence, etc., to provide a method for efficiently repeating the sequence to reduce the effect of the frequency offset.

RACH transmission method according to an aspect of the present invention for achieving the above object, receiving a signaling message from the base station to select one or more predetermined RACH structure, and RACH having a RACH structure selected according to the signaling message Transmitting a signal.

On the other hand, the RACH receiving method according to another aspect of the present invention, transmitting a signaling message for selecting at least one predetermined RACH structure to one or more user equipment, and a RACH signal having a RACH structure selected according to the signaling message Receiving the.

In this case, the one or more predetermined RACH structures may include a first type RACH structure having a length of 1 TTI, a first type RACH structure including a preamble, a third type RACH structure having a length of 2 TTIs, and including a preamble; It may include a sixth type RACH structure having a 3 TTI length and including one preamble, in which case the signaling message from the base station distinguishes the first type RACH structure and the third or sixth type RACH structure It may include 1 bit information.

In addition, the predetermined one or more RACH structures, the first type RACH structure having a 1 TTI length, including a preamble, the second type RACH structure having two TTI lengths, and including two preambles, 2 A third type RACH structure having a TTI length, including one preamble, a fifth type RACH structure having three TTI lengths, a third type RACH structure including two preambles, and a three TTI length, including one preamble And a sixth type RACH structure, in which case the signaling message from the base station includes two bit information for distinguishing the first, second, third or sixth, and fifth type RACH structures. can do.

In addition, the predetermined one or more RACH structures, the first type RACH structure having a length of 1 TTI, including a preamble, the third type RACH structure having a length of 2 TTI, including a preamble, 3 A fourth type RACH structure having a TTI length and including three preambles, and a sixth type RACH structure having three TTI lengths and including one preamble, in which case signaling from the base station The message may include two bit information for distinguishing the first, third, fourth, and sixth type RACH structures, whereas the signaling message from the base station may include the first, third, or sixth, first It may include four type RACH structures and two bits of information for distinguishing a certain RACH usage that can be represented by one bit.

Further, the one or more predetermined RACH structures may have a length of 1 TTI, a first type RACH structure including one preamble, a second type RACH structure having two TTI lengths, and two preambles; A fifth type RACH structure having a TTI length and including two preambles, and a sixth type RACH structure having a three TTI length and including one preamble, in which case from the base station The signaling message may include two bit information for distinguishing the first, second, fifth, and sixth type RACH structures, whereas the signaling message from the base station may include the first, second, or fifth, It may include sixth type RACH structures and two bit information for distinguishing a certain RACH usage that can be represented by 1 bit.

In addition, the predetermined one or more RACH structures, the first type RACH structure having a 1 TTI length, including a preamble, the second type RACH structure having two TTI lengths, and including two preambles, 2 A third type RACH structure having a TTI length and including one preamble, and a fifth type RACH structure having a 3 TTI length and including two preambles, in which case signaling from the base station The message may include two bit information for distinguishing the first, second, third, and fifth type RACH structures.

In addition, in the above-described embodiments, the length of the preamble included in any one of the third and sixth type RACH structures may be the same as or different from the length of the cyclic prefix CP.

On the other hand, the sequence repetition method according to another aspect of the present invention, a method for performing a sequence repetition for channel signal transmission, repeating a predetermined sequence two or more times, each repeating portion of the sequence repeated two or more times Dividing into two or more portions, and sequentially placing portions having the same order among the two or more portions separated in each repeating portion of the repeated sequence two or more times.

In this case, when the predetermined sequence is repeated twice in the repeating step, and each repeating part of the repeated sequence twice in the separating step is divided into two parts of the first part and the second part, in the disposing step, The first portions in each repeating portion of the two repeated sequences may be arranged contiguously, followed by the first portions so that the second portion in each repeating portion is contiguous, and The method may further include applying a circular shift to one or more repeating portions of the sequence repeated two or more times between the repeating step and the distinguishing step.

The method may further include masking each repetitive portion of the sequence repeated two or more times using a sequence having the length of the two or more repetitions, wherein the channel signal is a channel signal requiring estimation of a frequency offset. Can be.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form around the core functions of each structure and device in order to avoid obscuring the concepts of the present invention.

In order to support large cells in RACH transmission, a method of repeating preambles has been proposed. Currently, a basic RACH structure in the 3GPP LTE field is proposed to have a total length of 1.0 ms and a preamble length of 0.8 ms, and to support a cell having a radius of 15 Km as described above through the RACH structure. Can be.

However, as described above, under the presently advanced UTRA structure, the RACH is required to support up to a cell having a radius of 30 Km, which corresponds to twice the radius that the basic RACH structure described above can support.

In consideration of various round trip delays under such a situation, various types of available RACH structures may be shown in Table 1 below.

type RACH length RPF Cell size (km) Parameters One 1.0 ms One ~ 15 CP = 0.1 ms, preamble = 0.8 ms, GT = 0.1 ms 2 2.0 ms 2 15 to 30 CP = 0.2 ms, preamble = 1.6 ms, GT = 0.2 ms 3 2.0 ms One 30-90 CP = 0.6 ms, preamble = 0.8 ms, GT = 0.6 ms 4 3.0 ms 3 30-45 CP = 0.3 ms, preamble = 2.4 ms, GT = 0.3 ms 5 3.0 ms 2 45 ~ 105 CP = 0.7 ms, preamble = 1.6 ms, GT = 0.7 ms 6 3.0 ms One 45-120 CP = 0.8 ms, preamble = 0.8 ms, GT = 1.4 ms

In Table 1, "RPF" represents a repetition factor, that is, the number of repetitions of the preamble, "CP" represents a length of a cyclic prefix, and "GT" represents a length of a guard time. Indicates.

Various RACH structures described above with reference to Table 1 will be described in detail with reference to FIG. 1 below.

FIG. 1 is a diagram illustrating RACH structures supporting a plurality of TTI lengths to support a large cell and having various numbers of preamble repetition structures.

As can be seen from the first through sixth type RACH structures of Table 1 shown in (a) to (f) of FIG. 1, the supportable cell size in various RACH structures is based on CP length and GT length It can be seen that it is determined by. That is, it can be seen from FIG. 1 and Table 1 that the approximately supported cell size increases by 15 Km per 0.1 ms of GP length. Thus, the above CP length and GP length can be determined according to the appropriate coverage area.

In addition, the RACH structure used may be determined in consideration of the number of repetitions of preambles allowed in the system.

If only two repetitions of the preamble are supported in the system, the first three types of RACHs of Table 1 and FIG. 1 (ie, first to third type RACH structures) may be used to support large cells. Can be. In this case, the basic RACH structure of the first type may be used within 15 Km of coverage, and the second type RACH having a preamble repeated twice may support up to 30 Km, has a length of 3 TTI, and has one preamble. The third type RACH having can support up to 30 ~ 90 Km.

In addition, if three repetitions of the preamble are supported in the system, the first, second, fourth, and fifth type RACH structures of Table 1 and FIG. 1 may be used within a coverage area according to each RACH structure. have.

In addition, in an embodiment of the present invention, in consideration of the coverage area according to the CP and GT lengths as described above, the number of preamble repetitions allowed in the system, as well as the number of bits for signaling the available RACH structure, It is proposed to define a set of possible RACH structures, so that the following RACH structure combinations can be used.

Combination (type) Number of signaling bits Permissible RPF Maximum supported cell size (~ Km) One 1, 3, 6 One One 15/90/120 2 1, 2, 3, 5, 6 2 2 15/30/90/105/120 3 1, 3, 4, 6 2 3 15/90/105/120 4 1, 2, 5, 6 2 2 15/30/105/120 5 1, 2, 3, 5 2 2 15/30/90/105

In Table 2, the type index included in each combination refers to the type index for the RACH structure of Table 1, and the number of signaling bits indicates the signaling necessary for the base station to inform each UE by distinguishing the RACH structures included in each combination. The maximum allowable RPF indicates the maximum number of preamble repetitions allowed in the system, and the maximum supportable cell size indicates the size of the supportable coverage area according to the RACH structure included in each combination.

Specifically, according to the first combination, first, third and sixth type RACH structures may be used. In this case, since the third type RACH and the sixth type RACH have the same preamble length, the base station does not need to separately indicate them to each UE, and by leaving the CP length and the GT length blank according to each type used, the UE RACH signal can be distinguished. Therefore, in case of supporting the above three RACH structures, the base station has an advantage of notifying the RACH structure used for each UE through a 1-bit signaling message.

In addition, according to the second combination, first, second, third, fifth, and sixth type RACH structures may be used. In this case, as described above, since the base station does not need to separately inform each UE of the third type RACH and the sixth type RACH, the base station may inform the RACH structure used for each UE through a 2-bit signaling message. .

In addition, according to the third combination, first, third, fourth and sixth type RACH structures may be used. In this case, as described above, the third type RACH structure and the sixth type RACH structure do not need to be notified by the base station to each UE. However, even if they are not distinguished, a two-bit signaling message is required to indicate three cases. Therefore, the four RACH structures described above may be distinguished and represented through this signaling message. However, another embodiment of the present invention does not distinguish between the third type RACH structure and the sixth type RACH structure, and the other one of the four cases that can be represented by the aforementioned 2-bit signaling message is used for another purpose. It may be set to indicate a particular use of the RACH (eg, indicating a control channel, overlapping a data channel, etc.).

In addition, according to the fourth combination, first, second, fifth and sixth type RACH structures may be used. In this case, since the second type RACH structure and the fifth type RACH structure have the same preamble structure, the base station does not need to separately inform the UE as described above. Accordingly, a two-bit signaling message may be set to represent four RACH structures included in the fourth combination described above, as in the third combination, or a second of the four RACH structures included in the fourth combination described above. Without distinguishing the type RACH structure from the fifth type RACH structure, one of the four cases that can be represented by the aforementioned 2-bit signaling message may be set to indicate a specific use of the RACH.

In addition, according to the fifth combination, first, second, third and fifth type RACH structures may be used. In this case, the base station may inform the aforementioned four RACH types through a 2-bit signaling message.

The combination of the RACH structure as described above with respect to Table 2 may be applied in a manner in which the RACH structure to be used in the signaling message in each system is used and the UE transmits the RACH signal through the determined RACH structure.

It is also possible to support a plurality of RACH structures among RACHs of various structures included in the combinations shown in Table 2 above in one system. For example, when one system uses a plurality of RACH structures, a long RACH designed based on a UE located at a cell edge may be located at the cell center by using different RACH structures according to positions of UEs in a cell. The UE may also prevent resource waste by using the same.

Meanwhile, the length of the preamble included in any one of the third and sixth type RACH structures described above in the combination of Table 1 and Table 2 may be equal to the length of the CP (for example, shown in Table 1). As can be seen, both the preamble length and the CP length may be 0.8 ms). However, the length of the preamble and the CP length may be set somewhat differently from those shown in Table 1.

In addition, in various RACH structures shown in Table 1, the CP length may be longer by a predetermined length than the value shown in Table 1, and the GT length may be shorter by a predetermined length than the value shown in Table 1.

Meanwhile, in the following, when the sequence is repeatedly applied for the purpose of the RACH preamble sequence or the like according to another aspect of the present invention, a method of efficiently repeating the sequence in order to reduce the influence of the frequency offset will be described.

When the preamble length is increased by increasing the RACH length to support a large cell, the simplest method may simply repeat the sequence applied to the preamble. This is the same as the case of the second, fourth, and fifth type RACH structures shown in FIG. 1 and Table 1 above. According to such a structure, the preamble and correlation characteristics of another UE may be maintained, and different cell sizes may be supported according to repeated preambles.

However, in the case of simply repeating the preamble in this way, the range of the frequency offset that can be supported may be limited (for example, in the case of the second, fourth and fifth type RACH structures of Table 1, up to 625 Hz). Only up to frequency offset range can be supported).

Accordingly, one embodiment of the present invention is to provide a method that can support a larger frequency offset range by reducing the repetition period of the sequence by dividing each repetition portion within the repetition portion of the sequence applicable to the preamble. do.

FIG. 2 is a diagram for describing a sequence repetition method for reducing the influence of a frequency offset when a preamble sequence is repeated twice in accordance with an embodiment of the present invention, by dividing the preamble sequence into two parts. FIG.

Specifically, in one embodiment of the present invention as shown in FIG. 2, each repeating portion (ie, preamble 1 and preamble 2) of the original preamble sequence repeated twice is shown as shown at the top of FIG. 2. It is divided into two parts of the first part and the second part (ie, the first part and the second part of the preamble 1, and the first part and the second part of the preamble 2).

As described above, the first parts of the preamble 1 and the preamble 2 of the two parts divided in each repeating part sequence are arranged to be continuous to the front end as shown in the lower part of FIG. The portions can be arranged to follow the first portions.

FIG. 2 illustrates a form in which a first portion of preamble 1 is disposed, a first portion and a second portion of preamble 2 are disposed, and a second portion of preamble 2 is arranged, thereby illustrating a process of sequence relocation. Although an example of a method of simplicity is shown, a specific arrangement method may be in a different order, for example, a first part of preamble 1, a first part of preamble 2, a second part of preamble 1, The second part of the preamble 2 may be arranged sequentially.

When repeating the sequence according to the embodiment as shown in Figure 2, compared to the conventional second, fourth and fifth type RACH structure of Table 1 that preamble using a sequence having the same length is free It can be seen that the amble duration is cut in half, thereby increasing the range of supportable frequency offsets up to 1250 Hz. That is, according to the above-described embodiment, the frequency offset may be less sensitive than the case of simply repeating the preamble sequence.

Meanwhile, in a preferred embodiment of the present invention, the preamble sequence may be repeatedly applied as described above with reference to FIG. 2, and the additional information may be displayed by applying a cyclic shift to at least one portion of the repetitive portion. Hereinafter, a detailed description will be given with reference to FIG. 3.

3 is a diagram for describing a method of repeatedly applying a sequence according to one preferred embodiment of the present invention and applying a cyclic movement to a portion of the repeating portion.

FIG. 3 illustrates a structure in which a sequence repetition method according to an embodiment of the present invention described above with reference to FIG. 2 is applied in a more general manner. That is, in the case where the preamble sequence is applied twice, each repeating part is divided into two or more parts, and the parts divided in each repeating part of the sequence are rearranged in order. As shown in FIG. 3, when each sequence repeating part is divided into a plurality of parts, each of the divided parts may be divided into chip levels. As described above, when each repetitive part of the sequence is divided into a plurality of parts, the repetition period of the preamble is reduced according to the number of divisions, and the range of frequency offsets that the RACH can support is increased in proportion to the number of divisions described above. Can be.

In addition, in a preferred embodiment of the present invention, as shown in FIG. 3, the circular movement may be applied to any one or more portions of the plurality of sequence repeating portions to display additional information. Specifically, assuming that the unit for dividing each sequence repeating part is chip level in FIG. 3, a cyclic shift is applied to the second sequence repeating part (ie, preamble 2) over two chips. Accordingly, in the structure in which the sequence is repeated according to the preferred embodiment of the present invention at the bottom of FIG. 3, the portions separated from the preamble 2 are rearranged by two chips compared to the portions separated from the preamble 1. Able to know.

According to one preferred embodiment of the present invention, when the cyclic shift is applied to a predetermined part of the repetitive part of the sequence, as described above, additional information may be indicated and timing estimation due to repetition of the same sequence part may be performed. Can reduce the inaccuracy of That is, in FIG. 3, the preamble 1 and the preamble 2 correspond to repeated portions of repeating the same sequence. If the same portions are divided and rearranged, timing estimation may be difficult as the same portions of each sequence are repeated. . However, after applying the cyclic shift to any one of the preamble 1 and the preamble 2 (for example, preamble 2) repeating the same sequence according to a preferred embodiment of the present invention as shown at the bottom of FIG. In the case of rearranging them into a plurality of parts, the ambiguity of timing estimation due to the repetition of the same sequence part as described above may be reduced.

On the other hand, the problem to be solved in order to enable the RACH channel to support a large cell, there is a problem of increasing the RACH length and the problem related to the frequency offset, as well as the lack of usable sequence as described above. That is, when the RACH is used in a large cell, the number of available sequences can be reduced because it is difficult to apply cyclic shift to the sequence due to the large propagation delay.

Accordingly, another embodiment of the present invention proposes a method of masking and using a predetermined sequence in a sequence to be applied to a preamble in order to solve the problem that the number of available sequences is insufficient as described above.

4 is a diagram for describing a method of masking and applying a predetermined sequence to a preamble sequence according to another embodiment of the present invention.

Specifically, FIG. 4 illustrates masking each preamble sequence using a sequence of length 2 when the preamble sequence is repeated twice. If the preamble sequence is repeated R times, the masking sequence according to the present embodiment may use a sequence having good cross-correlation / autocorrelation characteristics having a length R. Preferably, the masking sequence herein may be an orthogonal sequence, but any masking sequence may be used when the correlation characteristic of each preamble sequence is not degraded.

As shown in FIG. 4, a method of masking using a predetermined sequence in the preamble sequence may be applied in parallel with the embodiments of the present invention described above with reference to FIGS. 2 and 3. This is because the repeating portion of each preamble includes the entire sequence portion, even in accordance with each embodiment of the present invention described above with reference to FIGS. 2 and 3. Further, when masking is performed using a masking sequence having good correlation characteristics as described above with respect to FIG. 4 in each embodiment of the present invention described above with reference to FIGS. 2 and 3, the arrangement of the entire sequence is rearranged. As a result, the correlation property may be compensated to some extent.

Meanwhile, the sequence repetition method according to each embodiment of the present invention described above with reference to FIGS. 2 to 4 has been described with an emphasis on the case where the RACH preamble is applied. However, such a method may be applied to other channels. . For example, a sequence repetition method, a cyclic shift application method, and a sequence masking method as described above may be applied to a synchronization channel (SCH), a sounding channel (CQ channel, etc.), a pilot channel, etc. in a 3GPP LTE system. In addition, the above-described scheme may be applied to the preamble in the IEEE 802 series system. That is, the method according to each embodiment of the present invention as described above can be applied to any channel requiring estimation of the frequency offset as well as the RACH preamble.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the present invention has been presented for those skilled in the art to make and use the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

According to the method according to an embodiment of the present invention as described above, the number of signaling bits to indicate these structures among the various RACH structures having a plurality of TTI lengths to support a large cell, and whether to use a preamble repetition structure And a combination of available RACH structures according to the number of repetitions and the like.

In addition, when the sequence is repeatedly applied to a channel requiring the estimation of the frequency offset, according to the above-described embodiments of the present invention, it is possible to support a system having a higher frequency offset.

Claims (17)

Receiving a signaling message from a base station to select a RACH structure among a predetermined combination of one or more RACH structures; And And transmitting, by the UE, the RACH signal through the RACH structure selected according to the signaling message. The signaling message indicates the type index of the RACH structure for the UE to transmit the RACH signal of the combination of the RACH structures, Each of the RACH structures in the combination of the RACH structures is set to have a different length of a cyclic prefix (CP) and a repetition number of the preamble sequence, and the RACH structure in which the UE transmits the RACH signal may include the RACH structure. RACH transmission method according to the type index. The method of claim 1, The predetermined combination of one or more RACH structures is A first type RACH structure having a length of 1 TTI and including one preamble; A third type RACH structure having a length of 2 TTI and including one preamble, and A sixth type RACH structure having a length of 3 TTI and including one preamble, The signaling message from the base station includes one bit information for distinguishing the first type RACH structure and the third or sixth type RACH structure. The method of claim 1, The predetermined combination of one or more RACH structures is A first type RACH structure having a length of 1 TTI and including one preamble; A second type RACH structure having a length of 2 TTI and comprising two preambles, A third type RACH structure having a length of 2 TTI and including one preamble; A fifth type RACH structure having a length of 3 TTI and including two preambles, and A sixth type RACH structure having a length of 3 TTI and including one preamble, The signaling message from the base station includes two bit information for distinguishing the first, second, third or sixth, and fifth type RACH structures. The method of claim 1, The predetermined combination of one or more RACH structures is A first type RACH structure having a length of 1 TTI and including one preamble; A third type RACH structure having a length of 2 TTI and including one preamble; A fourth type RACH structure having a length of 3 TTI and including three preambles, and And a sixth type RACH structure having a length of 3 TTI and including one preamble. 5. The method of claim 4, The signaling message from the base station includes two bit information for distinguishing the first, third, fourth, and sixth type RACH structures. 5. The method of claim 4, The signaling message from the base station includes the first, third, or sixth, fourth type RACH structures, and two bit information for distinguishing a certain RACH usage that can be represented by one bit. The method of claim 1, The predetermined combination of one or more RACH structures is A first type RACH structure having a length of 1 TTI and including one preamble; A second type RACH structure having a length of 2 TTI and comprising two preambles, A fifth type RACH structure having a length of 3 TTI and including two preambles, and And a sixth type RACH structure having a length of 3 TTI and including one preamble. The method of claim 7, wherein The signaling message from the base station includes two bit information for distinguishing the first, second, fifth, and sixth type RACH structures. The method of claim 7, wherein The signaling message from the base station includes the first, second, or fifth, sixth type RACH structures, and two bit information for distinguishing a certain RACH usage that can be represented by one bit. The method of claim 1, The predetermined combination of one or more RACH structures is A first type RACH structure having a length of 1 TTI and including one preamble; A second type RACH structure having a length of 2 TTI and comprising two preambles, A third type RACH structure having a length of 2 TTI and including one preamble, and Includes a fifth type RACH structure having a length of 3 TTI and comprising two preambles, The signaling message from the base station includes two bit information for distinguishing the first, second, third, and fifth type RACH structures. The method according to any one of claims 2 to 10, The length of the preamble included in any one of the third and sixth type RACH structure is the same as the length of the cyclic prefix (CP). Transmitting a signaling message to one or more user equipment to select a RACH structure among a predetermined combination of one or more RACH structures; And Receiving a RACH signal from the user equipment through a RACH structure selected according to the signaling message, The signaling message indicates a type index of a RACH structure for the user equipment to transmit a RACH signal among the combination of the RACH structures, Each of the RACH structures in the combination of the RACH structures has a different length of a cyclic prefix (CP) and a repetition number of preamble sequences, and the RACH structure for receiving the RACH signal from the user equipment is the RACH structure. Determined according to the type index of the RACH. In the method for performing sequence repetition for channel signal transmission, Repeating the predetermined sequence two or more times; Dividing each repeated portion of the sequence repeated two or more times into two or more portions; And And sequentially placing portions having the same order among the two or more portions separated from each repeating portion of the repeated sequence two or more times in a row. 14. The method of claim 13, When the predetermined sequence is repeated twice in the repetition step, and each repetition part of the sequence repeated twice in the dividing step is divided into two parts of the first part and the second part, In the disposing step, the first portions in each repeating portion of the two repeated sequences are arranged to be continuous, and the first portions are arranged so that the second portion in each repeating portion is subsequent to the first portions. , Sequence iteration method. 14. The method of claim 13, Between the repeating step and the distinguishing step, And applying a circular shift to at least one repeating portion of the sequence repeated two or more times. 14. The method of claim 13, Masking each repetition portion of the sequence repeated two or more times using a sequence having the length of the two or more repetitions. The method according to any one of claims 13 to 16, And the channel signal is a channel signal requiring estimation of a frequency offset.

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